Refrigerating apparatus



Feb. 5, i946. y J. L.. GxBsoN Filed J 30 1943 APatented Feb. 5,1946

REFRIGERATING APPAiiA'rUs J Lowell Gibson, Dayton, Ohio, assigner to General Motors Corporation, Dayton, Ohio, a corporation of DelawareA Application June 30, 1943, Serial No. 492,848

(Cl. (i2- 115) 3 Claims.

This invention relates to refrigerating apparatus and more -particularly to an improved arrangement which makes it possible to operate a retrigerating system efficiently 'over a wide range of pressure differentials.

One object of this invention is to make it practical to use the same 4-vane rotarycompresser design for use in air conditioning sys-v storage srystems and thev tems as used on cold like. 4

Another object of this invention is to provide a compressor with two parallel discharge ports one of which remains open at all times and the other of which opens only at lower compression ratios.

It has been found that the usual form of pressure operated outlet valves are not practical in A.i-vane rotary compressors wherein compressed gas is discharged from the compressor 4 times for every revolution of the compressor since the noise produced by such a valve is objectionable maintained in the evaporator in accordance with well known practice. The element i8 may be a fixed restrictor, a thermostatic expansion valve or any other type of control. `The type of controls used would of course depend upon the particular application and the temperatures desired.

Reference numeral designates generally a 4-vane rotary compressor having a main cylinder 22, a rotor 24, a drive shaft 2B, an inlet port 28, outlet means- 30 through which compressed refrigerant is discharged into the compressor casing 8l, an oil relief port 32, and vanes 34 not weaken the wall of the compressor too much and the wear and tear on the valve is very great.

Itis one object of this invention, therefore, to provide a valving arrangement in which a presw sure operated outlet valve is used but is not required to open and close each time a vane passes thereby.

A further object of this invention is to provide a valve having a natural period of vibration such that the valve does not have time to close between successive discharges from the compresser.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.

In the drawing:

Fig. 1 is a diagrammatic view of a refrigerating system incorporating my invention;

Fig. 2 is a sectional view taken on line 2-2 of Fig. 1;

Fig. 3 is an elevational view with parts broken away showing the compressor cylinder; and

Fig. 4 is a plan view of the valve disc.

Referring now to the drawing in which I have disclosed a preferred embodiment of my invention, reference numeral iii designates generally a sealed motor compressor unit which withdraws refrigerant vapor from the evaporator I2 through the suction line I3 and discharges compressed -refrigerant into the condenser it. The refrigerant condensed in the condenser it collects in the receiver IS from whence it flows through a conventional expansion valve i8 into the evaporator i 2. In the system shown, the flow of refrigerant from the evaporator to the compressor 50. hexagonal plate portion and a central boss 52.

is controlled by the back pressure regulating provided with shoes 36. For purposes of illustration, the outlet means has been shown in Fig. 1 as comprising two holes in the wall of the compressor 20 whereas in actual practice any number of holes may be used so long as they d o or offer too much restriction to the flow of refrigerant. The compressor shown herein is conventional except for the construction and arrangement of the outlet ports. Two separate outlet ports 88 and i@ are provided which communicate with the main outlet means 30 as shown in Fig. 2. The outlet port 38 is of conventional construction and remains open at all times and functions much the same as any outlet port in a 4-vane compressor. For .purposes of illustration, the outlet port lill which serves as an auxiliary port has been shown as comprising four openings which are displaced from the port means 38 as shown in Fig. 2. The number of openings which make up the auxiliary port is broadly immaterial. Since all of the valves for the openings forming the auxiliary port d@ are identical in 'construction and operation and since a single valve could be used, reference will be made to only one of the valves in the following description. Thus each of the openings forming the port d@ is provided with a pressure operated valve plate 42 which is biased to the closed position by means of a spring di which abuts against astop 4B threaded into an aperture d8 as best shown in Figs. 2 and 3. This valve never opens except at low compression ratios when the pressure of the gas in the compression chamber exceeds the outlet pressure before the outlet port 38 is uncovered.

As shown in Fig. 4 the valve plate 52 includes a The one end of the spring M surrounds the boss 52 so as to properly position the parts. By making the plate portion 50 of the valve plate 42 hexagonal, more clearance is provided for the escape of the gas.l

The spring d and the valve plate t2 are purposely designed so that the valve plate i2 has a natural period of vibration which in effect prevents the valve plate from moving into fully closed position each time compressed gas is discharged from the compressor at the low compression ratios.

the valve plate I2 in valve closing position whenlever the pressure Vwithin the compression chamber does not exceed the pressure on the high side of the refrigerating system.

Y The primary purpose of the spring 4l is to hold By virtue of the above described construction and arrangement the only outlet port which operates as a port at high compression ratios is the port 38. When the compressor is connected to a reirigerating system in which the compression ratios-fall below a predetermined ratio preferably 3% to 1 or thereabouts, the auxiliary port l0 will also function since at these compression ratios the pressure within the compression chamber will exceed the outlet pressure before the port 3l becomes uncovered. At these low compression ratios Y ascenso condenser means and said evaporator means i'ot the valve plate I2 will remain in the open position continuously while the compressor is operating. There will be certain transition periods when the compression ratio is such that very little of the gas is required to pass through the outlet port lo in which case the valve l2 will not move far od from its seat and may have a chance to close between each discharge from the compressor. Un-

der these conditions the valve does not have far to move and will not be noisy and will not be in- Vjurecl by the frequent opening and closing since under such conditions it cannot gain enough momentum in theshort distance through which it travels to become noisy or do any damage to the parts. As shown in Fig. 2 the: ports 4B and 38 both communicate with the main discharge openings 30. The above described valving arrangement makes it possible to use the same type of compressor design for those refrigerating systems having a high compression ratio as in those reirigerating systems having a low compression ratio. Furthermore a compressor incorporating my invention may be used ei'ciently in ,systems of the type wherein the compression ratio is high throughout certain periods of operation and is low throughout other periods of operation. Thus in the refrigerating system shown herein, the controls are such that the compressor is required to operate at high compression ratios for a portion oi the time and then required to operate at low compression ratios at other times. As shown in Fig. La pressure regulating valve i1 is placed in the suction line and is controlled by means of a thermostat i9. In the modification shown. the

thermostat i9 responds .to the temperature of the o refrigerant vapor at the outlet oi the evaporator. The thermostat I9 could; for example, be arranged so as to respond to the temperature, the relative humidity, or some other condition of the air either inside or outside the space to be conditioned.

While I have shown the equivalent of only one auxiliary valve port, it is obvious that additional auxiliary ports may be provided ahead oi' the mein outlet 88 and ahead of the port iid, The location of the oil relief port 82 may also be varied depending upon the number and location of auxiliary ports d and depending upon the type of olling system employed. The exact location of the oil relief port 32 does not form a part of my invention as oil relief ports of this type are commonly used in 4-vane rotary compressors so as to provide means of escape for lubricant in the event that the compression chamber becomes filled or partially illled with lubricant during the idle period of the compressor.

While the form of embodiment oi the invencontrolling the flow of refrigerant to said evaporator means; said compressor means comprising a casing forming an oil reservoir, a multiple vane compressor within said casing having a nrst out. let port and a second outlet port. one of said ports comprising a permanently open Dort and the other o! said ports comprising a pressure operated valve. and means for discharging the compressed refrigerant leaving Aone of said ports into said oil reservoir so as to drop out oil entrained by the refrigerant into said oil reservoir.

2.- In a refrigerating system; evaporator means;A

condenser means; compressor means; and means connecting said evaporator means. condenser means. and compressor means in refrigerant flow relationship; said connecting means including a pressure regulating means connected between said condenser means and said evaporator means for controlling the now of refrigerant to said evaporator means; said compressor means comprising a casing forming an oil reservoir, a multiple vane compressor within said casing having an inlet port, a first outlet port, and a second outlet port. one oi said outlet ports comprising a permanently open port and the other of said outlet ports comprising pressure operated valve means, and means for discharging the compressed refrigerant leaving said outlet ports into said casing so as to drop out oil entrained by the refrigerant into said oil reservoir; said connecting means including first connecting means connecting said evaporator means with said inlet port and second connecting means connecting the interior of said casing with said condenser means.

3. In a refrigerating system; evaporator means: condenser means; compressor means; and means connecting said evaporator means, condenser means, and compressor means in refrigerant ow relationship; said connecting means including a pressure regulating means connected between said condenser means and said evaporator means for controlling the flow of refrigerant to said evaporator means; said compressor means comprising a casing forming an oil reservoir, a multiple vane compressor within said casing having an inlet port. a. rst outlet port, and a second outlet port, one of said outlet ports comprising a permanently open port and the other of said outlet ports comprising pressure operated valve means, and means for discharging the compressed refrigerant leaving said outlet ports into said casing so as to drop out oil entrained by the refrigerant into said oil reservoir; said connecting. means including first connecting means connecting said evaporator means with said inlet port and second connecting means connecting the interior of said casing with said condenser means; and valve means provided in said nrst connecting means for controlling the pressure at the inlet of saidcompressor.

1'- LOWELL GBSON. 

